Windows only: Monitor any folder on your PC and automatically add new music to iTunes with freeware application iTunes Folder Watch. Just point it to the folder you'd like to watch for new music and let it work its magic. iTunes Folder Watch monitors the folder (or folders) for new music (i.e., music that doesn't already exist in iTunes) and can add music either automatically or queue it for you to selectively choose songs you'd like to add to iTunes. I once described a command line method for the same thing, but iTunes Folder Watch is a much simpler and full-featured solution. iTunes Folder Watch is freeware, Windows only, requires .NET; it's currently in beta, so expect a few bugs. Thanks Galley!